A 64-year-old man with a history of large-cell lung carcinoma and recent resection of a brain metastasis was examined because of a general decline in his ability to function. Whole-body positron emission tomography with fluorine-18 fluorodeoxyglucose (FDG PET) showed metastases along the spinal cord that were confirmed with MRI. Intramedullary spinal cord metastasis occurs rarely, and the prognosis is extremely poor. Whole-body FDG PET allows the entire spinal cord to be examined noninvasively compared with magnetic resonance imaging, computed tomography, and myelography.